Beam compass



July 25, 19.50 H. vlRus 2,516,735

BEAM coMPAss Filed Feb. e, 1947 Patented July 25, 1950 l UNITEDv STATES u 2,516,735 BEAM coMrAss Hugo Virus, Villa Park, Ill., assigner to Keuffel &

Esser Company, Hoboken,

of New Jersey N. J., a corporation Application February 6, 1947, serial No. 726,822

This invention relates to improvements in a beam compass. y

The invention is concerned primarily with providing means for adjusting one of the posts of a beam compass accurately to a predetermined position from which it will not be disturbed when it is firmly clamped to the beam.

Beam Compasses conveniently comprise a bar on which at least one post is movable, The other post may or may not be adjustable along the beam. In precision work with a beam compass it is necessary to adjust one post with respect to the other with a high degree of accuracy and various means have heretofore been provided to move the adjustable post along the bar. Devices of the prior art in many instances where capable of very minute adjustment but when the post was clamped to the bar the adjustment was frequently disturbed so that the original setting was lost. Other devices for accomplishing this purpose were oftentimes complicated and difficult to manufacture. This invention is shown as to its preferred embodiment in the accompanying drawings wherein;

Figure 1 is a View in elevation (with one part in section) showing the complete beam compass.

Figure 2 is a View in section of a portion of the adjustable post and the adjusting mechanism; and,

Figure 3 is a view in section along the lines 3-3 of Figure 2.

Referring to the drawings and particularly Figure l, the beam compass includes a bar or beam 2 which may be circular but is preferably irregular in cross section as my flattening a portion of the top (note Figure 3) in order that the two posts may be positioned on the beam and will not rotate with respect to each other.

For most purposes the bar or beam 2 is a single piece but for larger work it may be necessary to use an extension arm joint by a coupling 6. The coupling 6 comprises a tubular sleeve, the ends of which are split to form jaws 8. Threaded members iii at each end of the coupling sleeve l when screwed on to the sleeve cam the jaws 8 against the bar or beam to hold it against endwise movement. One post I2 may be xed t0 the beam or may be adjustable along the beam. Its construction basically is similar to that shown in greater detail in connection with adjustable post I4. To this end each of these include a body portion I6 having a suit-able opening to receive a needle, pencil or pen holding member I8. As illustrated member I8 is provided with a pin 20. Body portion I6 is drilled to receive the bar or 1l Claim. (Cl. 334-159) 2 beam 2 and extending portion is a threaded stern 22. -Slipped over the threaded stem 22 is a collar 24 having a flat bottom surface 2t to bear against ther flat top sur'- ace il of the beam 2. If the beam 2 has other shape than as illustrated, the surface 2-6 of the collar 2li should be appropriately shaped to bear against the top surface of the bar 2. A spring washer 28 is placed over the threaded portion and above the collar to help hold the post stem 30 in position when the post is released for adjustment. Referring now particularly to post I2 this is fastened in operating position at any lconvenient place along the bar 2 by slightly unscrewing post stem 3i! and sliding the post I2 to its position then screwing post stem 30 to force the coll-ar 24 rmly against the beam 2.

In the case of post I4, its basic structure is as described in connection with post I2 but in addition it may be provided with an extension sleeve 32 integral with body portion I6 and having a coaxial bore. Extension sleeve 32 has an extended counter part in the form of threaded extension sleeve Sli on the opposite side of body portion I6 which similarly has a bore coaxial with the bores of sleeve 32 and body portion I6. In the illustrated embodiment the extension sleeve 34 is externally threaded. A second threaded sleeve 36 is internally threaded to mesh with the external threads of threaded extension sleeve 34. A knurled ring 38 is fastened to the outside of second threaded sleeve 36 to rotate therewith as by a set screw 4G and is provided with an in-turned ange l2 which engages an out-turned ange 44 on a chuck 46. Chuck 46 may comprise two elements such as a split sleeve 4B carrying at one end the out-turned flange 44 and cam member 5i! to cam the split portion of sleeve 48 again@n the beam or bar 2.

In operation of the device, the post I2 is set in a predetermined position and the adjustable post I4 is moved along the bar until it is approximately in the correct position. Thereupon the chuck 46 is set on the beam by rotating cam member 5I) which tightens the split portion of sleeve 48 against the beam 2. The knurled ring 3B is then rotated in the proper direction to move the post I4 toward or away from the position of the post I2 until the two needle points 2|] (or other instruments at the end of the posts) are at exactly the desired distance apart as determined from a scale, drawing or other basic data. Thereupon the post stem 30 of post I4 is rotated a slight amount to force collar 24 firmly against the bar 2 to fix the post I4 in the adupward' between the body justed position. It will be noted that the action of fixing the post I4 in its adjusted position cannot in any manner change the relative position of the needle points 20.

It will thus be seen that this invention provides in a beam compass means for adjusting the posts very accurately and in a manner whereby they can be brought to the position of adjustment with great facility and clamped in adjusted position without disturbing the setting.

I claim:

A beam compass comprising a solid bar with a attened top surface, two posts at least one of which is slidable on the solid bar, both posts being held in the same plane by the fiattenedvtop surface of the bar, means for locking said slidable post to the solid bar, a rst externallyk said iirst externally threaded sleeve and inturned and out-turned flanges on said internally threaded sleeve and said split sleeve engaging each other around the bar so that when said split sleeve is locked to the bar and said slidable post is unlocked rotation of said internally threaded sleeve will cause an adjustment of said slidable post along the bar.

HUGO VIRUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 336,868 Pratt Feb. 23, 1886 638,805 Gordon Dec. 12, 1899 695,661 Theibault Mar. 18, 1902 FOREIGN PATENTS Number Country Date 560,261 Germany Sept. 30, 1932 628,639 Germany Apr. 8, 1936 

